Domains
The concept of the domain is very important to DVD navigation. A domain is a set of related program chains. These program chains are not related by presentational concepts such as play order or parental level. Instead, they are related by navigation commands. From the authoring perspective, all the program chains in a domain serve a common navigational role. From a playback perspective, the program chains in a domain constrain how the user can move both within and across domains. The following table summarizes the domains.
| Domain | What the DVD Navigator is reading |
|---|---|
| First Play | The initial section of the disc; for example, the FBI warning. |
| Video Manager Menu | The main menu for the entire disc or disc side. Any menu-related methods are valid. |
| Video Title Set Menu | The menu for a title or group of titles or one of its submenus — subpicture, language, audio, or angle. Any menu-related methods are valid. |
| Title | The video content in a title. The menu-related methods are not valid. |
| Stop | Nothing. The head is retracted from the disc. From here you can call Play. |
It is important to bear in mind the difference between navigation commands and user operations when working with domains. Navigation commands are authored into the DVD-Video content and therefore do not change over time or from one playback to another. They define how the DVD-Video elements in a specific recording connect to one another. For instance, it is the navigation commands that identify the specific program chain that corresponds to a specific title's video title set menu.
On the other hand, user operations originate from the user and are not part of the DVD-Video recording at all. A user is free to manipulate their player's controls whenever and however they want. Each manipulation can result in a user operation issued to the player. How the player acts on these user operations is dependent on the domain that the player is in.
Even though specific user operations are not, and cannot be, authored into a DVD-Video recording, the allowable set of user operations can, and must, be part of the recording. This allowable set of operations, and its outcomes, is authored into the program chains that make up a domain.
Last updated on Thursday, April 08, 2004
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